The present invention relates to a disk type information recording medium on which sound and/or video information is recorded by an optical method.
Conventionally, disk type information recording media such as shown in FIG. 2 have been used as recording media for use in systems for processing sound and/or video information.
FIG. 2 is a perspective view of the information recording medium, showing a cross section thereof. The information recording medium shown in FIG. 2 has a single information bearing layer a or two information bearing layers a, on one side or on both sides thereof. An inner spacer d and an outer spacer C are interposed between a pair of substrates b. Adhesive agent such as an epoxy adhesive or an ultraviolet ray setting adhesive is used to combine the inner and outer spacers d and C to the substrates b on both sides. The information recording medium f is formed in this way.
The information recording medium f has a hollow space e between two information bearing layers a on both sides, and a center hole g, at the center thereof, by which the information recording medium is clamped in a disk drive portion of an information processing apparatus.
However, in regard to conventional information recording media such as the medium explained above, there have been drawbacks in that, in the case of the epoxy adhesives, adhesive strength between the substrate b and the inner and outer spacers d, C is very low, although some of them are chemically stable against the material of the recording layer. In the case of the ultraviolet ray setting adhesives, workability in the manufacturing process is good and the adhesive strength is sufficient. However, the drawback is that the recording layer is damaged by gases (unreacted monomers or the like) produced as a result of setting of the adhesive.